1. Field of the Invention
The present invention relates to an apparatus for transferring substrates.
2. Description of the Related Art
Manufacturing semiconductor or flat panel displays such as liquid crystal displays and plasma displays requires a series of highly sophisticated processes.
Loading and unloading of wafers or substrates is be done to carry out each individual process. A method for transferring substrates into each process chamber by using a vertically moving carrier is utilized for the above loading and unloading.
FIG. 1 illustrates the structure of a conventional apparatus for transferring substrates.
As illustrated in FIG. 1, a carrier 13 comprises a loading unit 13C mounting substrates, an upper carrier bar 13A located inside a carrier guide 11A attached to an upper moving path, and a lower carrier bar 13B being in contact with a roller and driven for horizontal transfer by the movement of the roller.
The carrier 13 as above is transferred horizontally within a process chamber 10 or between chambers by an apparatus for transferring substrates comprising a upper transfer unit 11 and a lower transfer unit 12.
A conventional apparatus for transferring substrates has a problem that a lower carrier bar 13B attached to the roller of a lower transfer unit 12 is often displaced from the roller. Such a problem decreases yield, thereby reducing productivity.
In particular, since substrates are transferred being glued to a rotating roller, large friction force is generated and adverse effect due to particles may arise.